Conventionally, in various technical fields, a technique for removing a resist, once coated on a surface of the object to be processed from the surface thereof, has been known. For instance, in a field of manufacturing semiconductor devices, a method of using a processing fluid (or fluids) for peeling off the resist coated on the surface of each semiconductor wafer (hereinafter, referred to as a “wafer”) has been known. Specifically, a mixed processing fluid consisting of an ozone gas and water vapor is supplied into a processing vessel in which the wafers are placed, so that the resist coated on each wafer can be oxidized to be water-soluble by the mixed processing fluid. Thereafter, such a resist changed into a water-soluble state is removed by pure water. For instance, a processing system adapted for providing such a process to the object to be processed is disclosed in JP2003-332322A, and is typically composed of an ozone-gas generating unit for generating the ozone gas and a water vapor generating unit for generating the water vapor. In the system disclosed JP2003-332322A, the ozone gas generated in the ozone-gas generating unit and the water vapor generated in the water vapor generating unit are premixed together and then supplied into the processing vessel (e.g., see JP2003-332322A).
In such a processing system, in order to stably and efficiently make the resist water-soluble, it is required to keep the interior of the processing vessel, into which the mixed processing fluid consisting of the ozone gas and stem is supplied, at a predetermined pressure, during this process. Namely, during this operation, it is required to control discharge pressure and discharge flow rate of the mixed processing fluid from the processing vessel, by using a suitable means, for example, a flow-rate variable-control valve or the like.
Meanwhile, in a waiting period or the like, in which the process is not performed, the supply of the processing fluid into the processing vessel is stopped. Typically, during this period, the supply of the ozone gas and water vapor is stopped. Otherwise, the ozone gas and water vapor respectively generated in the ozone-gas generating unit and water vapor generating unit are discharged into the air or another suitable system.
In this conventional system, however, the flow rate of the processing fluid flowing through the flow-rate control valve is greatly changed between the processing period and the waiting period, the flow-rate control by means of the flow-rate control valve tends to be unstable at the beginning of the process, and thus it is impossible to immediately start the process in a relatively stable state.
In the case in which the processing fluid is discharged into the air through a separate system during the waiting period, the flow rate may be considerably changed between the period in which the processing fluid is supplied into the processing vessel and the period in which the processing fluid is discharged into the separate system. Therefore, substantial fluctuation of pressure may tend to be generated in a processing-fluid generating unit. Such fluctuation of pressure may be attributable to considerable change in an amount of the processing fluid generated.
Above all, in the case in which the processing fluid is supplied into a plurality of processing vessels from the processing-fluid generating unit, the fluctuation of pressure in each processing vessel may tend to occur, due to a difference in timing of supplying the processing fluid into each processing vessel or the like cause. Namely, the process performed in one processing vessel may have substantial influence on the process performed in another processing vessel, resulting in an unstable process in each processing vessel.
The present invention was made in light of the above circumstances. Therefore, it is an object of this invention to provide a new processing system adapted for processing the object to be processed, by supplying the processing fluid into the processing vessel, while significantly stabilizing the supply of the processing fluid into the processing vessel.